Electromagnetic driving system for timepieces

ABSTRACT

In an electromagnetic driving system for timepieces during the first half-oscillation of the oscillating member an astatic magnet system swings over only one coil inducing therein an impulse which opens two complementary transistors. The current flowing through the transistors and the coil creates a repellent impulse on the magnet system. The circuit includes blocking means rendering ineffectual the impulse induced in the coil during the second half-oscillation.

United States Patent Inventor Robert W. Reich Via Needs 8, CH-6977 Ruvigiilns- Lugsno, Switzerland Appl. No. 754,596 Filed Aug. 22, 1968 Patented Aug. 3, 1971 Priority Feb. 2, 1968 Switzerland 1,903/68 ELECTROMAGNETIC DRIVING SYSTEM FOR TIMEPIECES 11 Clsims,2 1mm; si V us. or ss/zs, 318/127 1111.01 G04c 3/04 ms 01 Search 58/23, 23 -23 rs, 2a TF, 28,28 A, 28 1;; 318/127, 129, 130-134 BIAS SOURCE 1,241,370 5/1967 Germany Relerences Cited FOREIGN PATENTS Primary Examiner-Richard B. Wilkinson Assistant Examiner-Edith C. Simmons AttorneySchwartz and Sarli ABSTRACT: In an electromagnetic driving system for timepieces during the first half-oscillation of the oscillating member an astatic magnet system swings over only one coil inducing therein an impulse which opens two complementary transistors. The current flowing through the transistors and the coil creates a repellent impulse on the magnet system. The circuit includes blockingmeans rendering ineffectual the impulse induced in the coil during the second half-oscillation.

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INVENTOR ELECTROMAGNETIC DRIVING SYSTEM FOR TIMEPIECES BACKGROUND OF THE INVENTION The present invention relates to an electromagnetic driving system for timepieces, for example watches.

All electromagnetic driving systems for timepieces and having transistor circuits and permanent magnets hitherto known, involve a driving coil and an excitation coil. This excitation coil is located in a basic circuit and the voltage produced in the excitation coil causes conduction of a transistor. Two coils are always necessary and these coils are either coupled to one another or lie next to one another or are located in any other way, such that the conduction of the transistor releases an impulse to the driving coil.

In addition, there are also circuits which operate with multivibrators or other electronic circuits in which impulses are produced from the circuit itself. This type of circuit is however very expensive and it is not used for mass-produced timepieces. It is only in mass-produced timepieces, watches in particular, that there is the problem of simplifying the circuit to reduce the expense in the cost of the coils and magnets as far as possible because these elements determine the eventual price of the timepiece. Above all, for wrist watches frequently the magnetic elements and several excitation coils are necessary because a single excitation coil is not sufficient. However, several excitation coils and magnet systems cannot usually be accommodated in wrist watches.

SUMMARY OF THE INVENTION One object of the present invention is to overcome the aforesaid drawbacks.

Another object of the invention is to provide an electronic magnetic driving system wherein only one single coil is arranged for receiving exciting impulses and retransmitting driving impulses.

A further object of the invention is to provide blocking means in the circuit in order to render ineffectual the exciting impulses induced in the coil during the second halt oscillation.

According to the present invention, electromagnetic driving systems for timepieces with permanent magnets on a mechanical oscillator and stationary coil means, or with oscillating coil and stationary magnets comprises a single driving coil, also, serves the purpose of supplying the excitation impulses for the control of the transistor circuit. Preferably, the pulses are decoupled capacitively or galvanically from the driving coil via high-locking diodes, Zener diodes or by way of transformer simultaneously from the same coil.

BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention will now be described, by way of example only, with reference to the accompanying circuit diagrams, wherein:

FIG. 1 is a circuit diagram of a first embodiment of a timepiece driving system according to the invention; and

FIG. 2 is a circuit diagram of a second embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the embodiment according to FIG. I, the coil 1 is connected between the negative terminal of a battery B and the collector of a PNP transistor 2, the emitter of which is connected to the positive terminal of the battery. Also, connected to the positive terminal of the battery is the base of an NPN transistor 4, the collector of which is connected to the base of the first transistor 2 and the emitter of which is connected to the battery negative terminal. The lead from the base of transistor 4 to the positive terminal contains a resistance 3. Between the base and the emitter of the transistor 4 is connected a silicon diode 5 of which the current flow direction is from the base to the emitter of transistor 4. In addition, the base of the transistor 4 is connected through a series circuit comprising a resistance 6 and a condenser 7 to the collector of the transistor 2. The coil 1 is located between the two poles of an astatic magnet system N-S which is'mounted on the insides of two parallel plates 12, 12a fixed to the axle of the oscillatory member of a timepiece. Two counter weights 10 face the magnet system N-S.

The electromagnetic driving system outlined above operates as follows. When the astatic magnet system N-S is swinging over the coil 1 in the direction of the arrow I, in the coil 1 a positive impulse is induced by which the NPN transistor 4 is biased to conduction according to the time constant given by the capacitance 4 and the resistance 6. In consideration of the threshold voltage the potential at the base of the transistor 4 is stabilized by means of the diode 5 in such a manner that the transistor current has a constant value. The conducting transistor 4 draws current from the base of PNP transistor 2; thereby the transistor 2 is biased to conduction, whereupon current flows from the positive terminal of the battery B through the transistor 2. Owing to the positive potential occuring at the collector of the transistor 2 the current flowing through the transistor 2 and the coil 1 increases like an avalanche due to the feedback and bears a repellent impulse on the magnet system N-S; as soon as the condenser 7 is charged completely, the cycle is ended. During the following second half-oscillation (in the direction of the arrow II) the transistor cannot be biased to conduction due to the reversal of the impulse induced in the coil 1, and for that reason no impulse having an effect on the magnet system N-S can be created. Not till during the following half-oscillation in the direction of the arrow I the above described cycle will be repeated.

In the embodiment according to FIG. 2, the driving coil 1 has one end connected to the collector of the PNP transistor 2, the emitter of which is connected to the positive terminal of the battery B and its other end is connected to the collector of the NPN transistor 4, the emitter of which is connected to the negative terminal of the battery. In parallel with the coil I is a condenser 8. From the emitter of the transistor 2 a lead containing a resistance 3 is connected to the base of the transistor 4; the base of the transistor 4 is also connected to the collector of the transistor 2 by a series circuit containing a resistance 6 and a condenser 7. A lead extends between the base of the transistor 2 and the collector of the transistor 4 and such lead embodies a resistance 9.

The operative of the FIG. 2 circuit is as follows. At first neither transistor is conducting and as the coil is in series connected to them no current can flow through the transistors. The impulse induced by magnet system N-S swinging over the coil 1 in the direction of the arrow I is applied to the base of the transistors 2 and 4; thus, both transistors will conduct simultaneously and current will flow from the battery B through the transistors 2, 4 and the interconnected coil I bearing a repellent impulse on the magnet system. The condenser 8 which is slowly discharged determines the switch'on time. During the second half-oscillation (in the direction of the arrow II) the transistors 2, 4 cannot be biased to conduction due to the reversal of the direction of current flowing through the coil 1, and for that reason no impulse having a repellent effect on the magnet system N-S can be created. During the following half-oscillation in the direction of the arrow I the above described cycle will be repeated.

In a modification of the embodiments illustrated in the drawing, the coil may be made up of several smaller coils in series. In any case, the necessity of having one or several excitation coils is dispensed with. By means of the movement of the magnets (for the coil in the magnetic field) a high-induction voltage is produced across the driving coil which is greater than the steady driving voltage across the driving coil due to the battery. This induced voltage is decoupled and placed on the base of the transistor 4. With modern silicon transistors, for example, with high amplification factor and very low ex citation currents this decoupled induction voltage from the driving coil can readily be used as an excitation impulse on the transistor base. It is also possible to decouple two induced voltages which are in phase opposition from outside to the middle point and from the middle point outwards also in a phase opposition manner and if a transistor PNP or NPN to work with necessary positive or negative current direction of the decoupled induction impulse for this transistor type. In this case there results two successive impulses which correspond only to one transistor in the phase and these impulses accordingly act on the vibrator on the one hand, attracting same, and on the other hand repelling same via the driving coil. The driving coil is inserted in the transistor circuit so that only the driving impulse in the required current direction can occur, attracting or repelling the vibrator via the control transistor and induction impulse. With phase opposition induction impulses and suitably connected PNP and NPN transistors the driving impulses are in phase opposition. Hereby, both transistors may be arranged next to one another as a completely independent circuit. They may, however, also be connected to one another by means of coupling members and the driving coil for the circuit is so arranged by means of capacitive, galvanic or inductive coupling so that for both phase opposition impulses also phase opposition driving currents occur.

Furthennore, there is the possibility of constructing the electronic circuit such that on the base of each transistor a biasing potential 13, 14 is applied so that only a very low-induction impulse brings about the conduction of the corresponding transistor. By means of the size of the condenser and of the corresponding load resistance for the production of the biasing potential a time constant for each transistor is formed which lies approximately in the same order of magnitude as the time constant which results from the speed of the mechanical vibrator and hereby there is brought about automatically the self-starting of the timepiece.

ln magnet arrangements which in the direction of vibration in relation to the zero position vibrating from the right or from the left, produce in the coil in the direction of flow alternating induction impulses, that is, therefore, when, for example, two pairs of magnets of opposite poles are present above and below in an astatlc system, whereby the conditions of the alternating impulses occur directly and are not prevented, the transistor circuit is so arranged that after each impulse the switch direction of the current changes in the driving coil for the transistor or the transistor.

The advantage of such an arrangement and use of the induction impulses is extremely great as very much simpler watches may be manufactured and such watches cost only a fraction of the hitherto known watchesusing an electronic circuit. Only a single coil is required irrespective of whether one works with only one or with several transistors and irrespective in which circuit this or these transistor or transistors is or are arranged. Hereby, the construction of the actual vibrator and the of the coil system is substantially simplified. ln wrist watches, arrangements are possible which are not possible with normal circuits with exciter and driving coils. Also, for many other types of watches, for the first time mechanical structures and electronic arrangements are possible which can be located in extremely small spaces; for example, the construction of travel alarm clocks in any normal travel alarm clock casing. The circuit cost is substantially less and the effect is very much better. Thus, for example, a watch which is provided with a normal excitation and driving coil and the appropriate magnet system draws about 5 to times the current of a watch constructed according to the invention. This is, above all, due to the fact that the whole winding space in which hitherto the exciter coil and driving coil had to be located is available for the driving coil alone. Hereby in the same space and with less expenditure a higher moment is attainable than with two coils on the same coil carrier and in the same thickness of the coils and the same diameter.

Furthermore, the thickness of wire for the exciter coil is different from that required for the driving coil. if one winds, for example, bifilar or if concentric coils are wound then each coil must be adapted to the necessary data of the transistor which is used. A driving coil must, therefore, for example, be wound with a wire thickness of 0.05 mm. and an exciter coil with a wire thickness of 0.03 mm. With bifilar coils a very large space is lost due to the use of different thickness of wire. With concentric coils there are available only very small annular coils for the drive as well as for the outer lying or inner lying exciter coil. With only a single coil one can arrange this optimally only for the drive of the suitable wire thickness and attain a much higher number of ampere turns in the same space. In ad dition, one obtains with the suitable use of transistors and the phase opposition decoupling in the same coil in two successive equal large impulses without more expenditure and accordingly a substantially higher driving force than with only a single small driving coil and exciter coil lying around. The current consumption of such a circuit is between 30 and 50 microamperes, while for normal watches with exciter and driving coil this is between 300 and 500 microamperes (large watches).

A further substantial advantage is that in a mass production the disposition of the amplification factor of the transistors does not enter the driving moment as is the case with exciter and driving circuit. In addition, the temperature dependence is substantially lower because the threshold voltage of the transistor is varied by 2 millivolts per degree Celsius, and the exciter voltage must be so arranged that also with lower temperatures even up to 20 or 40 degrees the voltage produced on the exciter coil still suffices to operate the transistor. This also completely falls away with the decoupling of the induction voltage as the induction voltage in any case is higher by powers of ten or at least by one power of 10 even with only a single coil and a magnet and this high induction voltage in any case operates the transistor. The existing voltage dependence for each transistor circuit can in the usual manner be compensated by Zener diode circuits or VDR-resistance in the circuit as in normal circuits. As an automatic self-starting of the watch results from the circuit no further expenditure for the carrying out of this self-starting is necessary. Collectively the advantages for the construction of watches according to the presentinvention are quite considerable and the technical progress utilizes all possibilities which have become possible today due to modern switch elements. The simplest watch which is to be constructed according to this method consists only of a stationary driving coil which is arranged optimally for the transistor and an astatic vibrating pair of magnets an the balance or on a pendulum and corresponding transistor circuit 'either for the single phase use of the induction impulse or for the phase opposition use with corresponding transistor circuits. in respect of the consumption of current and the manner of operation, the phase opposition transistor circuit with phase opposition control transistors is the most advantageous as it automatically gives in the same coil a double driving impulse of alternating direction.

A further considerable advantage in particular for wrist watches results from the fact that after l a driving coil is arranged which with transistors are driven next to one another as an independent circuit. In this way, one has the possibility of utilizing in the best possible manner the space which is available for the driving of the vibrating balance in a wrist watch because after vibration arc only in the correct transistor of the driving coil can also the correct driving impulse be given and after 180 a locking impulse can never occur. If one uses hereby two pairs of magnets arranged astatically after 180 then also the balancing and the position dependence for the wrist watch is reduced to a minimum an in fact without further expenditure. Hereby, therefore, any desired arrangement of coils and any desired transistor circuits can be used as one need never take into account any excitation impulses which lie wrongly or are added or removed as one has always only driving coils so that, therefore, in the whole amplitude of oscillation no retarding impulses can occur.

it will be understood that the above description of the present invention is susceptible to further modifications, changes, and adaptions, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.

lclaim:

l. in an electromagnetic driving system for timepieces having permanent magnets and coil means relatively movable against each other by means of a mechanical oscillator: an electronic circuit comprising; a pair of complementary transistors having their collectors connected to said coil means to form a series circuit; a direct current source connected between the emitters of said transistors to complete a series loop and biased to enable current flow through said loop; and circuit means connected between said coil means and the bases of said transistors for turning on said transistors in accordance with a signal generated by the relative movement of the permanent magnets and coil means.

2. The system of claim I further including means connected across said coil means for providing a predetermined switchon time for said transistors.

3. The system of claim 2 wherein said last named means comprises a capacitor.

4. The system of claim I wherein said circuit means comprises a first resistance means connected between said coil means and a base of one transistor.

5. The system of claim 4 wherein said circuit means further includes a second resistance means and a capacitance means connected between said coil means and a base of the other transistor.

6. The system of claim 1 further including a biasing potential means on at least one transistor base.

7. in an electromagnetic driving system for timepieces having permanent magnets and only one single coil relatively movable against each other by means of a mechanical oscillator a pair of complementary transistors, two capacitance means, at least two resistance means, a direct current source, the positive pole of which is connected to the emitter of the PNP-type transistor while the negative pole is connected to the emitter of the NPN-type transistor, and loadings connecting the individual components parts to each other as to form an electronic circuit, the improvement comprising the following features:

a. the collectors of the two transistors are connected to each other through the coil,

b. the collector of the PNP-type transistor is connected to the base of NPN-type transistor through the first capacitance means,

c. The collector of the NPN-type transistor is connected to the base of the PNP-type transistor through the first re sistance means,

d. the emitter of the PNP-type transistor is connected to the base of the NPN-type transistor through the second resistance means,

e. the second capacitance means is connected in parallel with the coil.

8. A driving system as defined in claim 7, wherein a third resistance means is series-connected to the first capacitance means.

9. A driving system as defined in claim 7, wherein each of the transistors is of the silicon type and has a biasing potential on its base.

10. A driving system as defined in claim 9, wherein each biasing potential is effected by a series connection of a capacitance means and a resistance means, the time constant resulting from said series connection having at least approximately the same value as the time constant resulting from the speed of the mechanical oscillator.

11. in an electromagnetic driving system for timepieces having permanent magnets and coil means relatively movable against each other by means of a mechanical oscillator: an electronic circuit comprising; a direct current source and only one singlecoil defining said coil means' a pair of complementary transistors; the emitter and coliector of a first PNP transistor of said pair connected in series with said direct current source and said coil defining an output circuit; a series connection of a capacitance means, a first resistance means, and a second resistance means connected in said order between the collector and emitter of said first transistor; a second capacitance means connected in parallel with said coil; and controlling means including a second transistor of said pair for biasing said first transistor to condition and releasing the current flow through said coil only as said mechanical oscillator effects a predetermined half-oscillation, said second transistor having its base connected to said series connection at a junction between said first resistance means and said second resistance means, its emitter and collector inserted between said direct current source and said coil, and its collector connected to the base oi said first transistor; and a third resistance means interconnecting the base of said first transistor with the collector oi said second transistor. 

1. In an electromagnetic driving system for timepieces having permanent magnets and coil means relatively movable against each other by means of a mechanical oscillator: an electronic circuit comprising; a pair of complementary transistors having their collectors connected to said coil means to form a series circuit; a direct current source connected between the emitters of said transistors to complete a series loop and biased to enable current flow through said loop; and circuit means connected between said coil means and the bases of said transistors for turning on said transistors in accordance with a signal generated by the relative movement of the permanent magnets and coil means.
 2. The system of claim 1 further including means connected across said coil means for providing a predetermined switch-on time for said transistors.
 3. The system of claim 2 wherein said last named means comprises a capacitor.
 4. The system of claim 1 wherein said circuit means comprises a first resistance means connected between said coil means and a base of one transistor.
 5. The system of claim 4 wherein said circuit means further includes a second resistance means and a capacitance means connected between said coil means and a base of the other transistor.
 6. The system of claim 1 further including a biasing potential means on at least one transistor base.
 7. In an electromagnetic driving system for timepieces having permanent magnets and only one single coil relatively movable against each other by means of a mechanical oscillator a pair of complementary transistors, two capacitance means, at least two resistance means, a direct current source, the positive pole of which is connected to the emitter of the PNP-type transistor while the negative pole is connected to the emitter of the NPN-type transistor, and leadings connecting the individual components parts to each other as to form an electronic circuit, the imprOvement comprising the following features: a. the collectors of the two transistors are connected to each other through the coil, b. the collector of the PNP-type transistor is connected to the base of NPN-type transistor through the first capacitance means, c. The collector of the NPN-type transistor is connected to the base of the PNP-type transistor through the first resistance means, d. the emitter of the PNP-type transistor is connected to the base of the NPN-type transistor through the second resistance means, e. the second capacitance means is connected in parallel with the coil.
 8. A driving system as defined in claim 7, wherein a third resistance means is series-connected to the first capacitance means.
 9. A driving system as defined in claim 7, wherein each of the transistors is of the silicon type and has a biasing potential on its base.
 10. A driving system as defined in claim 9, wherein each biasing potential is effected by a series connection of a capacitance means and a resistance means, the time constant resulting from said series connection having at least approximately the same value as the time constant resulting from the speed of the mechanical oscillator.
 11. In an electromagnetic driving system for timepieces having permanent magnets and coil means relatively movable against each other by means of a mechanical oscillator: an electronic circuit comprising; a direct current source and only one single coil defining said coil means; a pair of complementary transistors; the emitter and collector of a first PNP transistor of said pair connected in series with said direct current source and said coil defining an output circuit; a series connection of a capacitance means, a first resistance means, and a second resistance means connected in said order between the collector and emitter of said first transistor; a second capacitance means connected in parallel with said coil; and controlling means including a second transistor of said pair for biasing said first transistor to condition and releasing the current flow through said coil only as said mechanical oscillator effects a predetermined half-oscillation, said second transistor having its base connected to said series connection at a junction between said first resistance means and said second resistance means, its emitter and collector inserted between said direct current source and said coil, and its collector connected to the base of said first transistor; and a third resistance means interconnecting the base of said first transistor with the collector of said second transistor. 